15 June 2023

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Endodontic instruments fractured in the canals: how to locate them?

Simona Chirico

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Fracture of shaping instruments within root canals is a common undesirable incident in endodontics. These fractures can prevent proper preparation, disinfection and obturation of the canal. They can also cause significant sequelae on the outcome of endodontic treatment and have an impact on treatment planning. In addition, there are potential legal ramifications.

Radiographic evaluation is a crucial step in the management of endodontic complications but can be essential for the identification of fractured root canal instruments within the canals.

Conventional and digital periapical radiography (PAR) provide limited information due to the conversion of three-dimensional (3D) anatomy into a two-dimensional (2D) image. Therefore, the overlapping of anatomical structures may reduce its diagnostic efficacy.

Cone beam computed tomography (CBCT) allows for 3D evaluation of teeth and surrounding anatomical structures. In endodontics, CBCT is used to evaluate complications such as fractured instruments within root canals but has limitations, including higher patient radiation exposure than PAR.

Materials and methods

In a study published in Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology in September 2022, the authors compared the diagnostic efficacy of periapical radiography (PAR) with that of CBCT. They analyzed the effect with and without a metal artifact reduction algorithm (MARA) in the detection of fractured endodontic instruments, in plugged and non-obturated, straight and curvilinear canals. 

In total, 144 root canals of 48 mandibular molars were divided into four groups:

• Group 1 or control group with empty channels
• Group 2 or fracture group with fractured instrument in canal
• Group 3 or filling group with root canal filling, and
• Group 4 or fracture/fill group with a fractured instrument and root canal filling.

Teeth were radiographed by PAR using a complementary metal oxide semiconductor sensor and by CBCT without and with MARA to evaluate the diagnostic efficacy of the three techniques in detecting fractured instruments. Three examiners evaluated the radiographs.

Results

Overall, PAR showed significantly better diagnostic outcomes than CBCT without MARA. PAR produced significantly better results than both CBCT protocols in the presence of root filling and in straight canals. In the absence of filling in the curved canals, no statistically significant differences were found between the 3 techniques.

Conclusions

Periapical radiography is the imaging technique that best detects fractured instruments in straight obturated and non-obturated root canals.

However, researchers found no significant differences between the three imaging modalities in detecting fractured files in the absence of filling material in curved canals.

CBCT with MARA has shown greater sensitivity and specificity for the detection of fractured instruments in curved canals compared to straight canals.

For more information: "Diagnostic efficacy of three imaging modalities in the detection of fractured endodontic instruments: an in vitro study."